Heating means



R. A. WITTMANN 2 sheets-Sheet 1 "fill HEATING MEANS Filed March 23, 1939 March 11, 1941;4

2 Sheets-Sheet 2 HEATING MEANS R. A. WITTMANN Filed March 2.5; 1939 March 11, 1941.

surfaces farther Patented `Mar. 1l, 1941 I UNITED STATES 2,234,423 HEATING MEANS Robert A. Wittmann; Chicagm'I-ll., 'assigner to Thermek Corporation, Chicago, Ill., a corporation of Delaware 'Application March z3, 1939, sel-m1 Ivm-263,706

'zclaima The invention relates to liquid heaters.

In many water-heaters the water is circulated through one or more tubes and heated by the hot iiue gases from a gaseous fuel burner such as blue water gas, producer gas, carbureted water gas, natural gas, and various mixtures thereof. These gases have a high hydrogen content so that the flue gases from the combustion thereof have considerable moisture or vapor content. 'I'he combustion of ethane C21-Ie may be taken as an example. On complete combustion, such flue ga's sometimes contains approximately 30% water vapor content by weight. The temperature of the ue gases produced by the combustion of these gaseous fuels is usually dew points of gases having a high hydrogen content range upwardly from 100 F.

The heating tubes in these heaters through which the liquid ows are usually at a considerably lower temperature than the dew point of the hot flue gases. 70 F. is flowing through a heating tube, the tem perature of the outside of the tube may be approximately 80 F. The temperature Aof the surfaces extending from the heating tube and adjacent thereto will be 80 F. or somewhat higher. When heat transfer elements, such as fins, are used on the heating tube and a temperature of approximately 80 exists on the outer surface of the tube and the surfaces of the ns, there will be a zone between the wall of the tube and the flue gases passing around thetube at a temperature below the dew point while the heat transfer away from the tube wall will be at a higher temperature, such as 600 F. or more and this condition resulted in condensate where the ilue gases contacted with the portions of the surfaces of the tubes and said elementsY having temperatures below the dew point.

In constructions heretofore used, the conden' sate from the flue gases on-the heating tubes and transfer elements in ,the zone at a lower temperature than the dew point of the ue gases,

caused small percentages of S01 and other acidic constituents to be entrained inthe condensed water vapor, which bring about corrosion of the cold surfaces and thereby reduce the eciency of the transfer elements and shorten their life.- In some instances the water vapor condenses in suiiicient quantity to drip down on the gas-burner and close the gas-ports thereof, which 'produces vconditions which are undesirable both from structural and functional viewpoints.

-One object of the invention is to provide a heater of this type in which condensation from over 2000 F'. The- For example, when water at w series of heater-tubes .into which water is Voutwardly from its ywall (Cl. 122-333i the hydrogen content of.v the hot fuel gases will not be produced and deposited on the heating tubes or the heat transfer elements on the tube.

Another object of the invention' is to provide a water or liquid heater in which the ue gases are prevented from coming into contact with those portions of the heater-tube and itsheat transfer elements inthe zone around the tube where temperatures below the dew point are maintained.

. Another objectfof the invention is to provide `a method of preventing moisture condensation from hot flue gases on the heating surfaces byI shielding the latter where the .temperatures below the dew point of the hot flue gases exist or are maintained.- n

The invention consists in the several novel features which are hereinafter set forth and are more particularlydleflned by claims at the conclusion hereof. n f

In the drawings: Fig. 1 is a vertical section of a heater embodying the preferred form of the invention, the tubular structure through which the f water to be heated circulates being shown inelevation. Fig. 2 isa section taken on line 2 2 of 25 Fig. l. Fig. 3 is a side elevation of a portion of one of the heater tubes with the heat spines thereon. Fig. 4 is a section on line 4 4 of Fig. 3.

Fig. 5 is a section on line 5 5 of Fig. 3. Fig. 6 is a. section of a heater embodying a modied form of the invention. Fig. 7 is a section on an enlarged scale of a section of the heater tube of the form of the invention shown in Fig. 6. Fig. 8 is a section on line 8 8 of Fig. 7. Fig. 9 is a section of another modification.

In Figs. 1 to 5 the invention is exemplified in a heater comprising a jacket or body a and a with the hot ue gases blowing substantially parallel/to the tubes, a gas burner b in the lower portion of the body and an outlet a1 for the products of combustion. The structure through which the water or liquid .to be heated is circulated comprises an inlet-header I5 delivered through a supplypipe i6; 'a series of vertical tubes l'l, the lower 45 I5 so that water will ow from the header upwardly from said tubes; an outlet-header i8 in which the upperends of the tubes l'l are secured; and an outlet pipe 'I9 for the heated 50 Water or liquid leading from header I8. 'Each tube I1 is provided with helical series of spines 20 gouged from the stock in and bent to extend so that the spines will be fintegral with the tube.

.Adjacent the tube-,wall

" the tube andthe root l5 to prevent condensate which will exclude them tically approximatelyto the point 2| some distance away from the ,wall of the tube. The spines extend outwardly from tapered to pointed ends 22 another outwardly from point 2| sufliciently to 23 between them through which the flue gases can pass. Horizontal bailles 24 and 25 are secured inthe body and are provided with openings 26 whichl conform substantially to the outer endsof the spines to conne the hot nue gases in `their upward passage to the spaces 23 between4 the spines. The close and overlapping formationpf the spines 20 to the point 2| results in baming the hot flue .gases to substantially exclude them from the zone between the points 2| and the peripheries of the tubes. The spaces 23 betweenthe spines permit the hot nue gases to pass upwardly through the body and to contact with the spines for efcient heat transfer to the heating-tubes Il. y

' In the operation of this form of the invention the temperature of the hot ilue gases rising from the burner d is usually, and may be assumed to be, 2000 F. The dew point'of the hydrogen .content incertain gaseous fuels'will not exceed 138 F. In transit through the heater body a the ,nue gases' will be Ycooled by contact withv spines 20 and leave the-outlet a1 at approximately 350. 'I'he temperature at the outer ends of the spines will beapproximately 600 F. and, by reason of their high ratio of exposed area to their mass, 4serve as eillcient heat transfer elements or conductors to the tubes I1. The temperature at the points 2| of the spines will be somewhat more than 138 F. The temperature of the water as it passes through the tubes I1 increasesiirom-an approximate temperature4 of 70 at mid-height of the tubes while the temperatureof the tubewall may be approximately 80 F.

The` flue gases will p ass, upwardly through spaces 23 between the spines and the closely arranged and overlapping root-portions of the spines will form ay baiilefor the hot ilue gases from the zone between points 2l and -the wall of the tube. As a result, the flue gases will be substantially excluded from the zone around the heatingtube at which temperatures below the dew point exist. Asaresult, no condensatewill be deposited on the spines or tubing, there will be no corrosion of. the tubing and spines, and the other objections from the production of condensate will' be overcome.

This form of the invention exemplifies a heater in which the hot ilue'v gases travel substantially parallel with the tubing and the latteris pro` vided with spines, are contacted byv said gases for heattransfer to portions ofthe spines serve as a baille for excluding" the hot gases from a is so low that the hydrogen or water vapor would be condensed if it were not excluded therefrom.

The supply pipe I6 is provided with a cylindrical sleeve I5* between the wall of body aand heater of the supply pipe within the body.

In Figs. 6, '1 and 8, the invention is exemplified in -a hot water heater in which the fuel gases 'now transversely to the tubing. The heater com'- prises a body a2, a gas burner b1, and an -outlet a3 for the products of combustion] at the top of the body. A water supply pipe .I l" is connected to a tube 30 which islooped back and forth across the heating, chamber in the body and is connectedV the point 2| land are and diverge from one v 35. The cylindrical portions 3l the outer portions ofwhich forming on the portion .the gases and on the -tube and spines.'

to a hot water outlet 3 I Fins 32 are spaced apart lengthwise ot, and secured on, each of the horizon'tal portions of the tube 3l for heat transference to the tube.' Each nn has a central portion 33 which nts snugly around the outer periphery of the tube 3l, a relatively portion 35 and a cylindrical wall 34 spaced outwardlyfrom the tube and connecting 'portions 33, serve as spacers between the fins and form a continuous cylindrical baille around the outer periphery of the tube Ill.

In this construction the nue gases ilow verticallybetween and contact with the -nns for heat transfer to the tube. The cylindricalportions 3| forming the baille are so spaced from,the outer face oi tube 30 that the flue gases will not contact with the tube v3|) but only with the cylindrical baille. When the temperature of the water owirlg through the't'ube ranges from 'I0-80 F. the hot flue gases of approximately 200031". will contact with the fins and the outer portions of the baille and maintain a temperature around the baille ranging from 600 F. atthe outer ends of the ns downwardly to ajpoint which will maintain the temperature around the baiile above 138 F., the dew point of certain hot flue gases. As a result, the hot gases will not contact with any wall, the temperature of which is below the dew point, and no condensation will take place on the ns or onl the baffle and slow corrosion of the tube and the iins will be avoided. The dripping of water onto-the burner b1 will also be prevented. vention in which the hot flue gases flow transversely to the tubing. The tube 30 between the outer fins a and the surrounding wall of the body az is shielded by cylindrical sleeves 36 which are spaced from the tube to prevent condensation on these portions of the tube outside of the fins a. In Fig. 9, the invention is'exempliiied in a construction embodying fins a4 in the form of discs the inner edges of which are fitted around the tube 3| land cylindrical ,sleeves 33 spaced from the tube and extending between thediscs.

It will be understood that the temperatures referred toA are typical and may be modiiied according to theiparticular conditions existing in dierent heaters so long as the principle ofV excludingl the hot ue gases from the zone around the'tubing where temperatures below the dew point exists..

The invention is not to be understood as re-Y Having thus described the invention, what I claim as new and desire Patent isz' 1. In a liquid heater, the combination of a to secure by- Letters fburner for Agaseous fuel having a hydrogen content, a-tube through which the liquid ows, ex-

tending vlongitudinally of the now of the com' bustion gases from` the burner, and heat-exchange spines integral `with and,

wardly from the outer periphery of the tube, said spines having'their inner portions formed sume ciently close together `to exclude the hot iiue gases from the surfaces of the .tube and the por tions of the spines adjacent the tube in the zoneV below the dew point,-

where the ltemperatures are for preventing condensation of water vapor.in

of a

2.'In a liquid' heater, the combination offset outer This exemplies a form of the in-.-

extending outi burner for gaseous fuel having a hydrogen content, a tube through which the liquid flows, extending longitudinally of the flow of the -combustion gases from the burner, and heat-exchange spines integral with and extending outwardly from the outer periphery of the tube,'said spines having their inner portions formed sunlciently close together to exclude the hot ue gases from the surfaces of the tube and the portions of the spines adjacent the tube in the zone where the temperatures are below the dew point, for preventing condensation of water vapor in the gases and on the tube and spines, the outer portions of ythe spines having pointed ends so as to form outwardly divergent vV-shaped gaps between them through which the gases ow 1ongitudinally of the tube.

ROBERT A. WI'I'IMANN. 

